The sides of map-containing item frames are coplanar with block edges and as such are fully occluded by any adjacent blocks. As such, these sides are prime candidates for being culled in such situations.

Example culling by full blocks:

Example culling by other item frames:

It's worth noting that for some reason, map item frames also contain some inner planes that can never be seen without intersecting the frame, so it might be wise to just outright delete these faces from the model. I can provide a modified model json file if desired.

I believe the performance cost of checking the blocks is more expensive so I won't do this unless I make a block based entity system or a cached entity lookup that gets modified by block updates